Apparatus for mechanically separating mineral mixtures



E.- BiERBRAUER July 28, 1942.

APPARATUS FOR MECHANICALLY SEPARATING MINERAL MIXTHRES Qriginal FiledSept. 22, 1937 2 Sheets-Sheet l '/nuenzo/':

ERNST BIERBRAUER ATTORNEYS y 1942- E. BIEVRBRAUER 2,291,447

APPARATUS FOR MECHANICALLY SEPARATING MINERAL MIXTURES Original FiledSept 22, 1937 2 Sheets-Sheet 2 ERNST BIERBRAUER ATTORNEYS Patented July28, 1942 APPARATUS FOR MECHANICALLY SEPA- RATING MINERAL MIXTURES ErnstBierbrauer, Leoben, Germany, assignor to American Lurgi Corporation, NewYork, N. Y., a corporation of New York Original application September22, 1937, Serial No. 165,220. Divided and this application July 28,1938, Serial No. 221,843

21 Claims.

This application is a division of my co-pending application Ser. No.165,220 filed September 22, 1937 for Method of mechanically separatingmineral mixtures, now Patent No. 2,189,698,

dated February 6, 1940. l q

This invention relates to a device for separating coarse-grainedmixtures of substances and constitutes an improvement of the subjectmatter of my co-pending application Ser. No. 106,057 filed October 16,1936, now Patent No. 2,189,124 dated February 6, 1940, which deals witha process for dressing coarse-grained mineral mixtures by making use ofthe different, and if necessary artificially differentiated,adhesiveness of the constituents of the mixtures with respect to more orless solid inorganic or organic adhesion masses. 4

According to this process, the constituents of a mixture are separatedby superficially softening an adhesion mass and bringing it inthiscondition in contact with the mineral grains. During subsequentsolidification the mass firmly unites with the substance capable ofadhering thereto. Practical application of this separating method isusually effected by means of rotary drums or hands covered with anadhesion mass, on which the material to be separated is placed and whichare passed through-corresponding heating and cooling zones. Adheringgrains stick during reversal of the support, and the nonadheringsubstance drops off either automatically or after subjection to a slightmechanical operation,, such as tapping.

The employment of solidifying or hardening adhesion masses in the mannerindicated affords the advantage that the adhesive forces available forthe separation of the minerals are extraordinarily large and thus permitthe separation of coarse-grained substances. Notwithstanding the greatadhesive forces involved, the cohesion, or tendency to remain united, ofthe solid adhesion masses isstill greater than the adhesion to theadhering component of a mixture, so that the adhering grains can beloosened without pollution and without loss of adhesion mass. Thisadvantage which is particularly important in case organic adhesionmasses are used involves, however, drawbacks that become apparent in thepractical application of the process. Apart from the fact that theoperating equipment is complicated by heating or cooling devices, themanner of setting also has an unfavorable effect. The relatively longperiod of setting, which in granular mixtures of mm. to 30 mm, grainsize amounts for instance to approximately 1 to 2 minutes, naturallyresults in a comparatively small-output per unit of area of themechanical members provided with adhesion mass or requires very largeadhesive surfaces and consequently machines of large dimensions toattain big outputs.

The invention eliminates this diihculty and while retaining a mode ofoperation as free from pollution as possible insures considerableshortening of the adhesion process and thus of the throughput rate perunit of area of the adhesive mass.

Since the mechanical utilization of the accelerated adhering process bythe use of corresponding high-speed machines unavoidably developsadditional forces which counteract the adhesive forces, the inventionfurther provides for attaining an increased adhesive effect to compenesate these additional forces. It is only by the 'cooperation'of thesetwo factors that an optimum of the success aimed at by the invention canbe attained.

According to the invention, the acceleration and intensification of theadhesion process are attained by bringing the grains to be separatedinto intimatecontact with the adhesion mass under a certain applicationpressure instead of merely putting them on the mass, as was donehitherto. Adhesion will then occur the more quickly and intensively thelarger the contacting interfaces between the grains and the adhesionmass are. By employing solid yet more or less plastic adhesion agents,such as, up to a certain degree, ice, or, more decidedly, organicsubstances like thevarious kinds of bitumen, pitches, waxes and resins,contact over a particularly large area can be obtained by theapplication pressure. The'same, or even a still more increased, effectmay be produced according to the invention by applying the adhesionmasses to plastic or elastic supports consisting for instance ofcaoutchouc or cellular caoutchouc in which instance the adhesion massesneed not absolutely be solid plastic substances. According to theinvention, adhesion substances may be used also which consist of aplastic or elastic support provided with a filmy coat of a more or lessliquid adhesive, though the coat shall be a mere trace on the supportand united therewith by greatest possible adhesion, as then the sameadvantages and effects will be attained which result from the use ofsolid adhesion substances.

The application of the mineral grains to be separated to thecorrespondingly treated adhesion masses can be effected in differentways, namely, either by dynamically produced or static pressure, fromwhich different possibilities ensue for practical operation. Staticpressure, according to the invention, is transmitted by means ofyielding or elastic intermediate "substances, such as caoutchouc orcellular caoutchouc, etc., to the grains to be separated so as uniformlyto cover all grains irrespective of differences as size and shape. Theelastic intermediate means may for instance be used in such a mannerthat the grains to be separated lie on a rubber or spongy rubber plateand a plate provided with adhesion mass is pressed against the grains.Owing to the pliability of the elastic support, all grains will thuscome into contact with the adhesion mass, and

it depends entirely on the adhesive power of the individual grainswhether or not they will unite with the adhesion mass. When the plateprovided with adhesion mass is lifted, the adhesive grains will stick toit whilst the non-adhesive grains will remain on the rubber plate.

Owing to the pollution of the adhesion surface 1 the more or less solidadhesion masses, particularly the organic substances, gradually losetheir adhesive power, and the surface thereof must thereiorebe renewedfrom time to time. In the application ofthe process describedin my olderapplication, which provides for constantly alternating heating andcooling of the adhesion mass, the surface of the latter is automaticallyrenewed due to continuous softening, so that special measures anddevices forthis purpose can be dispensed with. The new method, however,based on the application of surface pressure, often, and particularlywhen organic adhesion masses are employed, requires additional measuresfor constantly maintaining uniform and intensive adhesion and therebythe fundamental conditions for continuously carrying out the pressureprocess. Regeneration could be effected for instance by putting on newadhesion mass, possibly by applying a new layer of molten petroleumbitumen to the existing layer if petroleum bitumen serves as adhesionmass. The surface of the adhesion mass may further be renewed byperiodic softening through heating so as to disclose itsinitialadhesiveness after resolidification. The same end can be attained bymechanical scraping of the used surface layer. f

A still simpler expedient is superficially to dissolve or soften theadhesive substances by chemical. action to renew or even to increasetheir adhesive power. When solid organic adhesive substances areemployed, regeneration and simultaneous intensification of adhesivepower are effected according to the invention by treating the surfacewith liquid or gaseous organic substances like petroleum and its variousproducts of distillation, benzine, benzene, phenol, cresol, toluene, orwithtar oils, parafiin oils, etc. The liquid organic regenerating agentsmay be used as such or as solutions containing the dissolved adhesivesubstance. It has further been found advantageous to employ the liquidregenerating agents in:

the form of aqueous emulsions, in which case only very slight amounts ofthe regenerating agents come into contact with the adhesion mass to beregenerated, so that the action is restricted to the surface. I

In addition to organic regenerating agents inorganic purifiers may beused. It has been ascertained for example that particularly sulfuricacid as well as other inorganic acids and bases are suited for thispurpose. The regenerating agent is either wiped off or dries orevaporates, so that within a reasonable time the desired firmcons'istency of the surface of the adhesion mass will be regained. Thissurface should be in such condition that in the dry state it feelssticky when a finger is passed over it, though the finger should notbecome soiled even at the exertion of greater pressure. This criterionis mentioned, because it demonstrates in a simple and clear manner thecondition of the surface of the adhesion mass as required by 'the newmethod and, further, because it illustrates the essential difference ofthe new.

method as to the nature and consistency of the adhesion mass usedcompared with those older methods 'whichemploy liquid organic adhesionagents for the separation of fine-grained mineral mixtures, apart fromthe fact that these older methodslack also artificial differentiation ofthe adhesiveness of themineral mixtures preferably applied according tothe invention, and by'their very nature are restricted to workingfinegrained mineral mixtures.

When instead of organic adhesion masses ice or .other solidifyinginorganic substances are used, the chief regenerating agents willbewater or aqueous solutions of the cementingor adhesive substancesconcerned.

The same effect as that produced by treatin'g:

the adhesion mass with the organic regenerating agents or their aqueousemulsions mentioned can be attained according-to the inventionby wettingthe grains to be separated withthe regenerating liquids afterpretreatment.

This step, which may also be carried out during pretreatment as statedbelow, increases'moreover, the adhesion of the adhesive grains to the,adhesion mass and thereby facilitates the practical application" ofthepending application Ser. No. 106,057. Substantially the sameor-similar,'usual- 'ly'water soluble, organic reagents are employed fordifferentiating the adhesiveness of the constituents of a mineralmixture, which in flotation practice serve as collecting agents fordifferentiating the wettingcapa'city or floatability. The a adhesivecapacity imparted during-this preliminary treatment to one kind'ofsubstances with respect to organic adhesionmasses can be essentiallyintensified according to the invention by adding to the aqueoussolutions of the collecting agents serving for artificiallydiiferentiatingadhesiveness water insoluble organic liquids, such as theabove mentioned regenerating agents The amount of addition should bechosen so that the adhesion of the treated substances relative to anadhesion mass consisting of, say, petroleum bitumen. Thisintensification is so strong that'even a much used adhesion surface towhich mineral grains not treated by this addition will not stick anymore discloses again greatadhesiveness so that regenerationmay bedispensed with. This manner of preliminary treatment i's'thereforehighly important for the practical application of the pressure methodand forms a valuable step therein. I

The following test which can be carried out with simple means willillustrate the pressure method.

The equipment required merely comprises a sponge rubber plate and asheet metal or wooden plate having about the same size. The latter iscovered on one side with a layer of petroleum bitumen having a meltingpoint of about 60 C. and being therefore solid at ordinary roomtemperature. The mineral mixture to be separated was a natural mixtureof about 50% phosphatic material, phosphorite in lumps and 50% gangue,quartzy rubble with a grain size of about 15 to 30 mm. As these twokinds of minerals in their natural water-wetted condition show noadhesiveness relative to the adhesion mass mentioned, the mixture wasfirst subjected to preliminary treatment for differentiation. For thispurpose the mixture was thoroughly worked for about 3 minutes with anapproximately 1% aqueous solution of sodium palmitate. During thistreatment selective adsorption of the palmitate to the surface of thephosphorite grains will occur, so that owing to the orientation of themolecules connected with adsorption the grains are provided with anouter skin of hydrocarbons and thus with an adhesive cover beingafiinitive relative to organic adhesion masses. As at this treatmentonly the phosphorite lumps react in the manner indicated and the quartzyrubble superficially does not undergo any change the result will be adifferentiation in adhesive power. When the pretreated mixture afterrinsing with water is placed directly on the adhesion mass mentionedadhesion of the phosphorite lumps capable of adhering will occur onlyafter a few minutes, which however, in spite of the long duration, isstill relatively slight. If the experimental conditions are, however,chosen according to the invention, instant and firm adhesion will beeffected, During the'experiment the surface of the adhesion mass wasfirst coated with a solution of petroleum bitumen in petroleum and thecoat allowed to dry. The phosphorite-quartz mixture pretreated withpalmitate and rinsed with water was then placed on a sponge rubberplate, whereupon the adhesion plate was applied to the grains at slightpressure. Directly after pressing the adhesion plate was lifted again,and it was found that almost all phosphorite grains firmly stuck to itwhilst the majority of the quartz grains remained on the rubber support.In this way a concentrate of 98% phosphorite at a phosphorite yield of94% could be attained.

. It has been stated already that the size of the area of contactbetween the mineral grains and the adhesion mass is decisive withrespect to adhesive intensity and that this interface can be increasedaccording to the invention by the use of plastic adhesion masses or byapplying adhesives to pliablebodies of plastic or elastic nature. Theeffect of this measure can also be proved by the small test described.For this purpose the adhesion mass was applied not to a rigid plate butto a sponge rubber sheet which was then secured to a corresponding rigidsupport. Otherwise, the mode of experimental procedure described wasfollowed again. The test showed an increase in the phosphorite contentof the concentrate to about 99% and a yield of 96% instead of 94%.Whilst the increase in yield is directly due' to the improved adhesioneffect brought about by the elastic adhesion plate, the higher degree ofpurity of the concentrate must also'be ascribed to the use of an elasticsupport for the adhesion mass. A few quartz grains,

particularly such having a particularly porous or,

jagged surface, stick to the adhesion mass together with the phosphoritegrains during pressing for purely mechanical causes. By the ex pansionof the rubber support of the adhesion mass at the cessation of pressurethese very loosely adhering quartz grains are pressed off again fromtheadhesion mass, and thisprocess constitutes-therefore an automaticafter-purification of the concentrate and, according to the invention,is utilized in continuous operation to obtain concentrates of thegreatest possible purity.

It was further proved by experiments that in the same manner and byusing the same reagent Magnesiteserpentinc, granulation 10 to 30 mm.

Magnesite Serpentine M agnesite Product ggfgg p content content yieldper cent: per cent: per cent:

Concentrate. 27.00 95. 0O 5. 00 95. 00 Tailings 73.00 2.00 93. 00 5.00Charge 100. 00 27. 20 72.80 100.00

SideriteQuartz, granulation 20 to 35 mm.

Siderite Quartz Siderite Product g ggg' content content yield per cent:per cent: per cent:

Concentrate. 63. 00- 96.70 3. 3'0 91. on Taihngs 37. ()0 4. 20 95. 3.00

Charge 100100 62. 40 37.60 100. 00

Experiments carried out with the same mineral mixtures, but employingfor the preliminary treatment an aqueous palmitate solution to whichabout 2% petroleum as added ledto still sharper separation andpermitted, moreover, the use of adhesion masses that were' quite usedup.

Instead of petroleum bitumen and other solid hydrophobe organic adhesionmasses inorganic adhesion masses, especially freezing water, wereexamined also. As to sharpness of separation,

practically the same results were obtained. The

process itself differs from the one applied in case of organic adhesionmasses in so far as the hydrophile gangue sticks While substances likephosphorite, magnesite, siderite, etc., which have become hydrophobeduring the preliminary treatment described do not show any adhesivepower relative to ice or other solidifying hydrophile adhesion masses.

As already mentioned all the organic agents used in the flotation fordifferentiating the fioatability are adapted to influencethe'adhesiveness. Therefore besides the salts of the fatty acids whichare especially adapted for alkaline earth minerals such as natriumpalmitate also the xanthates, further sulfonates of the alcohols. resinacids and resin soaps as well as aqueous emulsion of the oils may beused. The latter are especially advantageous if coals or rockscontaining organic ingredients shall be separated from barren rocks,profiting by the differences of adhesiveness. In numerous cases as tocoals, graphite'and the like their natural adhesiveness to organicadhesion masses is so great that'for the difierentiation of theadhesiveness a treatment with water only isfsuflicient. So it was forexample possible to separate according to the process described'amixture or coal and slates in a size of 30 to 60 mm. which was beforeonly treated with water.

Concerning the workability of grain sizes it was found that the newmethod covers grain 7 sizes ranging from approximately 1 mm. to 100,

mm. grain diameter. In practical operation, in the interest of thequality of separation it will be advisable to subject to separatematerial which does not differ too much in grain sizeand which has beenpreviously sorted by screening into classes each of which is then workedseparately by applying to it the pressure best suited to it.

The method according to the invention can be continuously carried out bythe use and suitable combination of simple apparatus and devices ofsubstantially known'type. In continuous operation these machinespreferably bring the material to be separated under regulatable pressureand with the aid of elastic intermediate means into contact with theconstantly or periodically to be regenerated adhesion mass anddischarge,

the adhering grains separately from the nonadhering ones.

By way of example, equipment for carrying out the method according tothe invention is illustrated the accompanying drawings, in which Figure1 is a view of a very simple device: Figs. 2 and 3 are views of similarconstructions: Figs. 4 and 5 show modified devices.

The device shown in Fig. 1 substantially comprises two horizontal rotarydrums or rollers a and b which move in opposite directions. The lowerdrum b serves for supplying material coming from the hopper c, and thetop roller a carries the adhesion mass and applies pressure. The lowerroller b is provided with a jacket of spongy rubber or similar elasticmaterial, and the top roller'u also has preferably a jacket of this typewhich serves as elastic support for the adhesion mass, for instancepetroleum bitumen. To permit'regulation of pressure the top roller a.can

move about the pivot e and the pressure can be adjusted by means of thecompensation weight f displaceable on the lever d. This leverarrangement aifords the added advantage of a particularly elasticseating of the application roller a and makes it possible to lift offthe pressure roller a from the feed roller b when the machine stops.Regulatable pressure could of course also be attained by elastic meansof other simple expedients, such as springs, rubber buffers, pressurecylinders, etc.

The grain mixture is separated in such mannor that the adhering grainsare, as it were, lifted out of the mixture by the top roller, whilst thenon-adhering grainsare dischargedgfrom the lower roller. A stripper gremoves adhering grains from the top or lifting roller a and lets themdrop into the discharge trough h, whereas the non-adhering grains aredischarged into the trough-k. Between the two discharge troughs h and itan adjustabl plate I serves for regulating discharge. The rollers a andb can be driven by providing a suitable drive (not shown) for the lowerroller 'b which then drives the upper one by friction. For constant orperiodic regeneration of the adhesion mass a suitable device may beused, which comprises for instance a troughn,

ing 20 revolutions per minute for handling phosphorite mixtureswith agranulation of approximately 15 mm. to 30 mm. hada throughput per hourof more than two tons. For the formerly mentioned mineral mixtures inthis way the same and partially even better results as to theseparationwere obtained, compared with the last given example.

Fig. 2 shows in'diagrani anarrangement, in which the lifting roller p isretained, but the material to be separated is fed suitably through ahopper c by means of the rotary" band 1, the band q and possibly alsothe roller p being covered with spongy rubber: The functions of thesetwo elements are similar to'those of the two rollers in Fig. 1;thusastripper g removes the adhering grains from the lifting roller pand lets them drop into the discharge trough h. In order to regeneratetheadhesion' masses covered on the roller p a suitable sprinkling devicet is provided above the roller p. The pressure of the roller p againstthe belt'q may be regulated by a lever d and a compensation weight Idisplaceable on said lever d as shown in Fig. 1'. om-' pared with theconstruction shown in Figs. 1 and 2 the device shown in Fig.3 issuperior in so far as a plurality of lifting rollers p may be arrangedfor picking one after anotherabove a conveyor belt q for instance toinsure repetition. The adhering grains are lifted by strippers g and theregenerating of the adhesion mass 'onthe rollers p is performed bysprinkling devices-t. In order to insure suflicient contact between theconveyor belt q which is coated with a rubber, rollers u,'v, w, arearranged on the inside of said belt q. i p

The same advantage is obtained by the device. shown in'Fig. 4 owing-tothe replacement'of the rollers bytwosuperposed rotating endless bands 1'and s which otherwise'are equipped like the rollers shown in Figs. 1'and 2. Where the two bands are in'contact, they are pressed together istructions shown inFigs. 1 and 2. As the material fed .by the band 8(Fig. 4) is for a longer time in pressure contact with the adhesion masson the band 1', adhering grainswill be fully lifted or picked'outwithout any repetition. The adhering grains stick to the top band 1',and are discharged by a stripper 9 into a bunker h. The non-adheringgrains are discharged by the lower band 8 during the reversal thereofinto a bunker k.

In Fig. 5 another modified construction is shown. Instead of a conveyorbelt or a feed roller a rotating table I; as shown in Fig. 5 may be usedon which one or more picking rollers a are disposed which should be'conical like edge runners. The arrangements described with 'refsweptfrom the table by stripper e into a trough k.

I claim:

1. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination a tacky adhesionmass of a material selected from the group consisting of hydrophilic andhydrophobic substances adapted to adhere selectively constituents ofsaid mixtures having at least more than 3 mm. diameter in accordancewith their wetness, a rotary surface coated with said adhesion mass, asecond surface on which the said coarse-grained mixtures are placed,means to cause said rotary surface to roll on said second surface, andan elastic means of sponge rubber forming at least one of said surfacesto exert a pressure when contacting the said surface coated with theadhesion -mineral mixtures.

2. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination a tacky adhesionmass of an organic hydrophobic substance adapted to adhere selectivelyconstituents of said mixtures having at least more than 3 mm. diameterin accordance withtheir wetness, a rotary surface coated withsaidadhesion mass, a second surface on which the said coarse-grainedmixtures are placed, means to cause said rotary surface to roll on saidsecond surface, and an elastic means of sponge rubber forming atv leastone of said surfaces to exert a pressure when contacting the saidsurface coated with the adhesion mass with said second surface coveredwith said mineral mixtures.

3. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adhesivenessrelative to adhesionmasses, comprising sion mass, a second surface onwhich the saidcoarse-grained mixtures are placed, means to cause saidrotary surface to roll on said second surface, and an elastic means ofsponge rubber forming at least one of said surfaces to exert a pressurewhen contacting the said surface coated with the adhesion mass with saidsecond surface covered with said mineral mixtures.

4. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination a tacky adhesionmass adapted to adhere selectively constituents of said mixtures havingat least more than 3 mm. diameter in accordance with their wetness, arotary surface having a sponge rubber covering coated with said adhesionmass, 8. second surface having a sponge rubber covering on which saidcoarsegrained mixtures are placed, means to cause said rotary surface toroll on said second sponge rubber covering, and means to exert apressure between such surfaces during said rolling.

5. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination a tacky adhesionmass of a material selected from the group consisting of hydrophilic andhydrophobic substances adapted to adhere selectively constituents ofsaid mixtures having at least more than 3 mm. diameter in accordancewith their wetness, a rotary surface having a sponge rubber coveringcoated with said adhesion mass, a second surface having a sponge rubbercovering on which said coarse-grained mixtures are placed, means tocause said rotary surface to roll on said second sponge rubber covering,and means to exert a pressure between such surfaces during said rolling.

.6; An apparatus as claimed in claim 1 in which said first rotarysurface is a conical drum and said second surface is a rotary member.

7. An apparatus as claimed in claim 1 in which said first rotary surfaceis a conical drum and. said second surface is a rotary member, spongerubber forming said second surface.

8. An apparatus as claimed in claim 1 in which said first rotary surfaceis a conical drum and said second surface is a rotary member, spongerubber forming said first surface.

9. An apparatus for the mechanical separation mixtures'to said firstrotary drum and to exert pressure thereon, a sponge rubber coating atleast on said second rotary drum, and means for separately dischargingthe said constituents of different adhesiveness to said adhesion mass.

10. An apparatus as claimed in claim 1, in which said surfaces arerolls.

11. In an apparatus as claimed in claim 1 means for regenerating theadhesion mass.

12.'An apparatus as claimed in claim 1, in which said surfaces arerolls, means for stripping the adhering grains from said adhesion mass,a trough adapted to contain a liquid, a feed roller in said trough and amoistening roller in contact with said feed roller and said adhesionmass.

13. An apparatus for the mechanical separation of coarse-grained mineralmixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination an adhesion massadapted to adhere constituents of said mixtures having at least morethan 3 mm. diameter, a conical rotary drum having a sponge rubber layerthereon coated with said adhesion mass, a rotary table on which saidrotary drum rolls, means to exert pressure during rolling of said drumon said table, andmeans for charging said mineral mixtures on said tableand for discharging the non-adhering constituents thereof from the tableand the adherin ones from said drum.

14. An apparatus for the mechanical separation of coarse-grained mineralmixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination an adhesion massadapted to adhere constituents of said mixtures having at least morethan 3 mm. diameter, a rotary conical drum coated with said adhesionmass, a rotary table on which said rotary conical drum rolls, means toexert pressure during rolling of said conical drum on said table, andmeans for chargingsaid mineral mixtures on said table and fordischarging the non-adhering constituents thereof from the table and theadhering ones from said conical drum.

15. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination an adhesion massof amaterialselected' from the group consistingofhydrophilic andhydrophobic substances adapted to adhere selectively constituents ofsaid mixtures having at least more than 3 mm. diameter in accordancewith their wetness, a plurality of rotary drums,

coated with said adhesion mass, a rotary band of sponge rubber, meanstocause said rotary drums to roll on said rotary band, means to exert apressure of said rotary drums on said band, means for charging saidcoarse-grained mixtures on said band, and means for discharging theadhering siveness relative to adhesion masses, comprising,/

constituents thereof from said adhesion masses on said drums.

16. An apparatus for the-mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination a tacky solidadhesion mass of a material selected from the group consisting ofhydrophilic and hydrophobic substances adapted to adhere selectivelyagainst the action of gravity constituents of said mixtures having atleast more than 3 mm; diameter in accordance with their wetness, asurface coated with said adhesion mass,

a second surface on which the said coarse-grained mixtures are placed,and means to exert a pressure when contacting the said surface coatedwith the adhesion mass with said second surface covered with saidmineral mixtures.

1'7. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures b the difference of their constituents in adhesiveness'relative to adhesion masses, comprising incombination' a tacky solidadhesion mass of a material selected from the group consisting ofhydrophiiic and hydrophobic substances adapted to adhere selectivelyagainst the action of gravity constituents of said mixtures having atleast more than 3 mm. diameter in accordance with their wetness, arotary surface coated with said adhesion mass, a second surface on whichthe said coarse-grained mixtures are placed, means to cause said rotarysurface to roll on said second surface, and means to exert a pressurewhen contacting the said surface coated with the adhesion mass with saidsecond surface covered'with said mineral mixtures.

18. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adheincombination, a tacky solid adhesion mass of an organic hydrophobicsubstance adapted to adhere selectively against the action of gravityconstituents of said mixtures having at least more than 3 mm. diameterin accordance with their wetness, a rotary surface coated with saidvadhesion mass, a second surface on which the saidcoarse-grained-mixtures are placed, means to cause said rotary surfaceto roll on said second surface, and means to exert a pressure whencontacting the said' surface coated with the ad hesion mass with saidsecond surface covered with said mineral mixtures.

19. An apparatus for the mechanical separation of wetted coarse-grainedmineral mixtures by the difference of their constituents in adhesivenessrelative to adhesion masses, comprising in combination a tackysolidadhesion mass of petroleum bitumen adapted to adhere selectivelyconstituents of said mixtures having at least more than 3 mm. diameterin accordancewith their wetness, a rotary surface coated with said adheesion mass, a second surface on'which the said coarse-grained mixturesare placed, means to.

cause said rotary surface to roll on said'second surface, andmeans-adapted to exert a pressure when contacting the'said surfacecoated with the adhesion mass with said second surface covered with saidmineral mixtures.- 20. An apparatus for the mechanical separationof-wetted coarse-grained mineral mixtures by the difference'of their,constituents rin adhesiveness relative to adhesion masses, comprisingincombination a rotary drum: having atacky solid adhesion mass coatedthereon of a material selected from the group consisting of hydrophilicand hydrophobic substances and adapted to adhere grains of said mixtureshaving at least more than 3 mm. diameter selectively against the actionof gravity in accordance with their wetness, a second vrotary drumadaptedjto feed the said mixtures to saidflrst rotary drum and to exertpressure thereon, andmeans for separately discharging the saidconstituents of different adhesiveness to said adhesion mass.

21. An apparatus for the mechanical separa tion of wetted coarse-grainedmineral mixtures by the difference of their constituents ,inadhesivenessrelative to adhesion masses, comprising in combination a tacky solidadhesion mass of an organic hydrophobic material adapted to adhereselectively against the action of gravity constituents of said mixtureshaving at least more than 3 mm. diameter in accordance with theirwetness, a surface coated with said adhesion mass, and means to exert apressure when con-,

tactingthe said surface coated with the adhesion with said mineralmixtures.

ERNST BIERBRAUER.

